The creep-damage constitutive and life predictive model for nickel-base single-crystal superalloys

A two state variable creep damage constitutive and life predictive model that has been built is discussed in this article. The cavitation controlled damage mechanism and microstructural degradation, i.e. material damage mechanism, are considered. The latter is derived mainly from the rafting and derafting of the precipitate gamma '. The model has been verified by the creep experiments of nickel base single crystal DD3 at 760 and 850 deg C. The steady creep and tertiary creep can be predicted satisfactorily. The active slip systems are confirmed as octahedral < 112 > {111} based on the lattice rotation. The parameter C reflecting material damage mechanism depends on the crystallographic orientation and can be assigned to the value C exp alpha sub < 001 > along < 001 > crystallographic orientation and C exp alpha sub < 011 > along < 011 > orientation partially. The life in different crystallographic orientations can be predicted satisfactorily.